On Saturday afternoon she remained in hospital in a critical condition.

Ms Tran was not known to the victim but was arrested 100m from the scene, tendered documents showed.

She smiled at television cameras as she was arrested and led to a police car on Friday morning.

Police are still searching for the passerby who went to the woman's aid.

He is described as being of Middle Eastern appearance, aged in his late-40s to early 50s with a medium build and dark short hair. He spoke limited English and was wearing casual clothing, including a dark jacket.

Homicide squad Detective Inspector Tim Day described the victim's injuries as "significant".

"For that to happen a significant altercation would have to have taken place," he said.

Willaton Street resident Michael Tran said he and another man found Ms Le bleeding heavily from her head and conscious, but unable to speak.

"I asked her in Vietnamese, have you been attacked? She nodded," he said.

The woman was found outside Mandy Kaur's home in Willaton Street.

A teary Ms Kaur said she did not see the attack nor know the victim, but she got out of her shower to see a crowd of people around the injured woman in her driveway.

"I saw her face full with the bleeding and her eyes swelling," she said.

"She didn't speak, she didn't open her eyes."

Ms Kaur said her neighbours had called an ambulance and police. She said she was shocked it happened in her neighbourhood.

"It's pretty safe. This is a first."

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.